LIKE Terms only applies partial term matching (compared to Fuzzy Matches which also performs primitive spell checking) which is useful when partial spell checking could wreak havoc on performance. Think partial matching for SKUs, for example.
By default SearchWP pulls results using all keywords in a search and weights them accordingly, highest weight wins. This extension allows users to exclude keywords from search results, e.g. “cats -dogs” would return search results including “cats” but not “dogs”.